Diuris secundiflora, commonly known as the one-sided donkey orchid, is a poorly-known species of orchid that is endemic to New South Wales. It has a single grass-like leaf and up to eight yellow flowers that are sometimes spotted and are all arranged on one side of the flowering stem.
Diuris secundiflora is a tuberous, perennial herb with a single leaf about 90sigfig=1NaNsigfig=1 long, 3sigfig=1NaNsigfig=1 wide and folded lengthwise. Between two and eight yellow flowers about 15sigfig=1NaNsigfig=1 wide are borne on one side of a flowering stem about 500sigfig=1NaNsigfig=1 tall. The dorsal sepal curves backwards, NaNsigfig=1NaNsigfig=1 long, about 6sigfig=1NaNsigfig=1 wide and egg-shaped to spatula-shaped. The lateral sepals are linear, NaNsigfig=1NaNsigfig=1 long, about 1.5sigfig=1NaNsigfig=1 wide and turned downwards. The petals spread widely or are more or less erect, egg-shaped, NaNsigfig=1NaNsigfig=1 long and about 5sigfig=1NaNsigfig=1 wide on a dark reddish brown stalk NaNsigfig=2NaNsigfig=2 long. The labellum is about 6sigfig=1NaNsigfig=1 long and has three lobes. The centre lobe is fan-shaped, 4sigfig=2NaNsigfig=2 long and 6sigfig=2NaNsigfig=2 wide with a central ridge. The side lobes are about 2sigfig=1NaNsigfig=1 long and less than 1sigfig=1NaNsigfig=1 wide. There are two thick callus ridges NaNsigfig=1NaNsigfig=1 long near the mid-line of the labellum. Flowering occurs in October and November.[1] [2]
Diuris secundiflora was first formally described in 1878 by Robert FitzGerald and the description was published in his book Australian Orchids.[3]
The one-sided donkey orchid is only known from the type location near the Macleay River "growing in a small cluster on an open bank".